Note: Descriptions are shown in the official language in which they were submitted.
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FLUID DELI~ERY SYSTEM
The present invention relates to a fluid delivery
system using a pressure pump, in which a pressure higher
than atmospheric pressure is applied to the fluid on the
intake side, especially for supplying fluids to a pressure
tank, e.g., to a carbonator for a post-mix beveraye dispenser.
To lower investmen-t costs and to achieve good
efficiency when delivering fluids, pressure pumps of known
construction are usually designed such that they satisfac-
torily meet requirements under normal operating conditions.
The usual prerequisite for normal operating conditions is
that fluid be present in the pressure-pump chamber. If no
fluid is available in the pressure pump chamber for delivery,
a dry cycle will occur endangering the pumping systems to a
high degree. Self-priming pumping systems are capable of
correcting this condition if fluid is available on the
intake side, but they are expensive to make and, aside from
that, their mode of operation is not particularly advantageous.
Therefore, for many fields of application~ non-self-
priming pressure pumps are the most expedient means for
delivering fluids. However, care must be taken that this
pressure pump be continuously filled with fluid, i.e., even
in the starting phase. Pressure pumps of this type are, for
example, used for delivering water to a carbonator of a
post-mix beverage dispenser in which refreshing drinks can
be prepared from water enriched with C02 and beverage concen-
trates. Water freshly supplied to such a carbona-tor is
enriched with pressurized C02 gas which is likewise supplied.
If required, additional fresh water must be delivered to the
carbonator against this pressure. As a rule a commercial
water supply with the necessary delivery pressure is not
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available. For this reason, a pressure pump must be incor-
porated into the water supply line for the carbonator.
Normally, replenishment of a carbonator with fresh water
occurs discontinuously, i.e., only if there is a new demand
due to the removal of carbonated wa-ter from the carbonator.
It may come to pass that, due to unfavorable circumstances,
a gas cushion enters the pump system. From the carbona-tor,
the pressure built up therein counteracts on the pressure
pump, so tha-t the gas cushion impeding the development of
the pumping action cannot be removed by the pumping action.
In order that the pressure pump can again operate properly
and not be exposed to adverse effects due to dry cycles, it
is necessary to vent the pump chambers, for example, manually.
A sui-table signalling system and the presence of
an attendant are necessary for this purpose. Depending on
the design, a temperature switch or a temperature fuse can,
in the event of overheating of the pump system, either turn
it off during periods of overheating -- which would lead to
repeated dry cycles -- or switch off the pump system perman-
ently until an attendant becomes available again to repair
the damage.
The present invention has for its object the
provision of a pressure-pump system for delivering fluids
and which offers a high degree of safety against dry cycles
of the pressure pump. A prerequisite therefor is that
fluid, in fact, be present at all times in the supply conduit
-to the pressure pump.
According to the invention, a fluid-delivering
system using, in particular, a pressure pump with non-self-
priming capacity that rneets these requirements is character-
ized by the fact that there is connected in parallel with
the pressure pump a differential-pressume system to which
pressure is applied to the pump intake on one side and to
the pump discharge on the other side, and which keeps open
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a vent value for the pressure-pump room when the
dif~erential pressure is lower than the normal delivery
pressure drop, and keeps this valve closed by the
working-pressure difference generated by the pressure
pump.
Various aspects of the invention are as follows: A
system for delivering fluids by means of a
pressure pump in which a pressure higher than
atmospheric pressure is applied to fluid at the intake
side of said pump comprising:
pressure sensor meansl connected in parallel to
said pump in fluid communication with the intake and
output side of the pump, for generating a vent signal
when the difference in flu.id pressure between said
intake and output side falls below a predetermined
level; and
vent valve means which opens for venting said pump
to the atmosphere in response to said vent signal.
A system for delivering fluids by means of a non-
self priming pump in which a pressure higher thanatmospheric pressure is applied to fluid at the intake
side of said pump comprising:
pressure sensor means, connected in parallel to
said pump in fluid communication with the intake and
output side of the pump, for detecting the presence of
gas cushions in said pump and for generating a vent
signal when the difference in fluid pressure between
said intake and output side falls below a predPtermined
level indicating the presence of a gas cushion; and
vent valve means which opens for venting said pump
to the atmosphere in response to said vent signal
thereby removing any gas cushion from said pump.
A system constructed according to these novel
features makes use o~ the fact that, if there is a gas
cushion in the pressure-pump system, the latter is
incapable not only of delivering fluids, but also of
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generating a pressure drop. Thus, if during operation
of the pressure pump no -- or only a moderate --
pressure drop can be detected, then one can draw the
opposite conclusion that gas has accumulated in the pump
room that has developed into a gas cushion. The
invention utilizes this Xnowledge by comparing with each
other, via a differential-pressure system, the pressures
on the pump intake and discharge sides. This
differential-pressure system controls a vent valve for
the pump room in such a way that the vent valve is kept
open if no -- or a moderate -- pressure drop is
discovered, and closed if the pump delivery pressure is
nurmal. Due to the pressure of the fluid flowing up
from behind the cushion, the gas cushion can escape
through the opened vent valve, so that the pump room
fills up again with fluid and the pressure pump can
again perform its function fully. Care must be
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taken that the air vent for the pressure-pump room be closed
by suitable means when the pump is not in operation, because
during shut-down times of the pressure pump there is no
pressure difference between its intake and discharge sides.
For example, a valve that can be controlled via electromag-
netic means is suitable for this purpose.
The system as taught by the invention can be sim-
plified by mounting the vent valve in -the differential-
pressure system on the pump discharge side. In this way, it
is unnecessary that the pressure pump itself be provided
with a vent valve. Another advantage is that the differential-
pressure system can act directly on the vent valve via a
control system.
According to a preferred embodiment, the system of
the invention is characterized by the fact that a backflow-
preventing valve is installed in the discharge conduit
downstream to the pressure pump and to the differential-
pressure system. The connection on the pump discharge side
for the differential-pressure system and the vent valve are
installed between the discharge of the pressure pump and
this backFlow-preventing valve, so that this region cannot
be controlled by the pressure of backflowing fluids.
According to another preferred embodiment, the
system incorporating the invention is characterized by the
fact that a flow restrictor is installed in the supply
conduit to the pressure pump. Thus, a substantially constant
fluid pressure is applied to -the pump intake side during
operation of the pressure pump.
Furthermore, a controllable valve which permits or
prevents the flow of fluid can be installed in pairs in the
fluid flow. During the delivery operation through the
pressure pump, this valve must be opened, while during shut-
down times of the pressure pump, it must be closed.
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A practical embodiment incorporating the features
of the invention is described in greater detail in the
following section by reference to the accompanying drawingz
in which:
The sole figure is a schematic representation
comprising a system for delivering fresh water to a carbonator
of a post-mix beverage dispenser.
From a storage -tank, but especially through a
public water-supply system, fresh water is passed through
line 1 to an electromagnetically controlled flow-shutoff
valve 2. IF this flow-shutoff valve 2 is opened by electro-
magnetic energization, the fresh water can flow therethrough
and through a flow restrictor 3 to the intake side 4 of a
pressure pump 5. This pressure pump 5 delivers this water
from its intake 6 via a backflow-preventing valve 7 to a
carbonator 8 in which this fresh water is enriched with C02
gas supplied under pressure via a line 9~ If desired, the
carbonated water, which is also cooled, can be removed from
the carbonator via line 10 to prepare a refreshing drink.
By means of a control system known from the prior
art and depending on the fluid level in the carbonator 8,
the pressure pump 5 can be turned on or off and the flow-
shutoff valve 2 opened or closed.
Particularly during the shut-down times of the
pressure pump 6 it is possible for gas to develop and to
accumulate to form a cushion in the pump housing, so that
the pressure pump 5 is no longer capable of delivery.
Therefore, there is installed between pressure-pump intake 4
and discharge 6 a differential-pressure system 11 having an
integrated vent valve 12. If, as a result of an air cushion
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in the room of pressure pump 5, the latter is incapable of
delivering water, no significant pressure drop can be
recorded between pressure-pump intake 4 and discharge 6. In
this case, the differential-pressure system 11 opens the
integrated vent valve, which is oriented towards the pump
discharge side, so that a pressure approaching ambient
atmosphere is produced on the pump discharge side. Water
flowing in through supply line 1 can now follow up from
behind into the housing of the pressure pump 5 and -force the
gas cushion therein through the vent valve. The pressure
pump 5, thusly refilled with water, delivers the latter
while building up a pressure drop between the pressure-pump
intake 4 and the pressure-pump discharge 5. The differential
pressure system 11 in turn closes the integrated vent valve
12.
By means of an electromagnetically controlled
passage-shutoff valve 13, which is triggered by electro-
magnetic means, together with the motor circuit for pressure
pump 5, it is possible during shut-down times of the pressure
pump 5 -- in which, of course, no differential pressure is
generated be-tween intake 4 and discharge 6 -- to prevent the
differential-pressure system 11 and the vent valve 12 ~rom
functioning.
The invention being thus described, it will be
obvious that the same may be varied in many ways. Such
variations are not to be regarded as a departure from the
spirit and scope of the invention, and all such modifications
as would be obvious to one skilled in the art are intended
to be included within the scope of the following claims.
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